Radio apparatus



April 3, 1928. 1,664,548

D. G RIMES RADIO APPARATUS Filed May 27 1922 6 Sheets-Sheet l April 3, 1928.

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D. GRIMES RADIO APPARATUS Filed May 27 1922 6 Sheets-Sheet 3 @5114 Gwen m1 April 3, 1928. 1,664,548

D. GRIMES RADIO APPARATUS Filed May 27, 1922 6 Sheets-Sheet 4 3440c for.

April 3, 1928.

D. G RIMES RADIO APPARATUS Filed May 27, 22 6 Sheets-Sheet 5 anvcutoc Dar/a r/mas elf om April 3, 1928. 1,664,548

D. GRIMES RADIO APPARATUS Filed May 27, 1922 6 Sheets-Sheet 6 &

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Patented Apr. 3, 1928.

UNITED STATES 1,664,548 PATENT OFFICE.

DAVID GRIMES, OF GRASM ERE, YORK.

RADIO APZBARATUS.

Application filed May 27,

closed within a cabinet and with no outside wires or connections.

More-spec1fically its ob ect is to improve the receiving elements and the circuits connected therewith.

These and other objects will appear in the following specification in which I will describe the invention, the novel features of which will be set forth in the appended claims. 1

Referring to the drawings, Fig. 1 is a perspective view of a cabinet within which all parts of the apparatus are contained.

Fig. 2 is a sectional side elevation showing more or less in outline an arrangement of parts within the cabinet.

Figs. 3, 4 and 5 are perspective views indicating a cabinet in dotted lines with a pivoted antenna in Fig. 3, a pair of spaced receiving surfaces in Fig. 4 and a novel form of spiral antenna in Fig. 5.

Fig. 6 is a wiring diagram of a receiving system'with a novel tuning circuit and with a novel form of loop antenna shown dia- Fig. 7 is a diagram of another receiving system with two loop antennae at right an les to each other and connected in series.

ig. 8 shows another arrangement of receiving instrumentalities with two loop antennae at right angles to each other and with a switch for connecting either of them with the other circuits.

Fig. 8 is a plan view of four loop .antennae. in angular relation connected with a selective switch.

Fig. 9 shows another arrangement of receiving instrumentalities with the novel tuning circuit of Fig. 6 and with two unlike and novel loop antennae at right anglesto each other and connected in parallel.

Like characters of .reference designate corresponding parts throughout the figures of the drawings.

10 designates a cabinet, preferably of rectangular form, within which all of the apparatus, including a closed oscillatory circuit comprising the antenna, is enclosed. 11 is 1922. Serial No. 564,227.

a plate upon which the detector and amplifier tubes and some of the other devices of a receiving circuit are mounted. This plate is spaced from the walls of the cabinet and rests upon cushioning members 12 of soft resilient material such as sponge rubber which are-held by brackets 13 aflixed to the cabinet. 14 is an amplifying horn, the large end of which extends to and is connected with the front wall of the cabinet which is cut away opposite this bell end of the horn. To its smaller end is aflixed a telephone receiver 15 which is held by a bracket 16 affixed to the rear end of the cabinet. In

Fig. 2 the A battery 17, the B battery 18, and a battery charger 19, are shown in the lower part of the cabinet. 19 (Fig. 1)

1s areceiving socket on one of the sides of the cabinet, which is connected with the intake conductors (not shown) of the battery charger. Fig. 2 also shows a loop antenna 20 parallel with and adjacent to the rear wall of the cabinet, and another loop antenna 29 parallel with and adjacent to one of the side walls of the cabinet.

In the modification shown in Fig. 3 a loo antenna 20 is mounted on a frame 21 which is pivotally connected in a bearing 22 at the bottom of the cabinet and in another hearing 23 above the horn 14. The position of this frame and antenna in relation to the cabinet may be adjusted by turning a knob 24.. When this form of antenna is used, the bracket 16 may be omitted and the horn 14. and telephone receiver 15 entirely supported from the front side of the cabinet so that the frame 21 may be rotated through about 90 degrees.

Instead of one or'more loop antennae,a pair of vertically spaced, substantially horizontal receiving surfaces 30, 31 (Fig. 4) may be used if desired.

' Or the necessary vertical and horizontal components of a loop antenna may be obtained by the use of the arrangement shown in Fig. 5.' This is a loop antenna having a central vertical portion 32 starting at a point near the upper part of the cabinet 10, and extending to the bottom thereof. From the lower end of this central portion an end portion 33 extends at right angles to one of the corners of the cabinet. From thence the wires lead upwardly along the sides of the cabinet forming diagonal parts 34, 35, 36, 37 having the same degree of vertical inclination, up to the same corner of the cabinet, and from this corner another transverse end portion 38 leads back to or near the point of beginning. It is obvious that an antenna of this kind when used as a part of an oscillatory circuit, is responsive to radiant electrical energy received from any direction.

In Fig. 6 I have shown a loop antenna. 20 connected in a regenerative detector circuit with two' steps of audio frequency aminner ones, and a still greater distance be tween the strands marked 26 and 27 and that this greater spacing increases pro ressively. The turns are however, still ept in substantial parallelism. It is the end of the loop which is connectedwith the grid of.

the detector tube-28 which is thus spread. This is because the voltage is highest at this 'part of the circuit and the capacity effects are greater, so that it is desirable to keep the turns of the loop farther apart.

40 is a coil having inductance and 4:1 a variable condenser. These together with the loop form the closed oscillatory circuit which can be tuned to respond to receive radiant energy by adjusting the condenser 41. 42 is another coil having inductance placed in cooperative variable relation to the coil 40. This is a well known arrangement for providing for feeding back energy from the late to the grid of the detector tube 28. I ave, however, provided a variable condenser 43 between the positive lead to the filament of the detector tube and the lead from coil 42 to an audio frequency transformer 44. This greatly helps the adjustment and is less critical than varying the inductive coupling between the coils 40 and42 although it works "m con'unction with them. It provides means or a fine adjustment of a regenerative circuit and is much more easily controlled than is the variable inductive couplin The capacit of the condenser 43 is as to enable t e L C value of this circuit to be tuned to resonance with coil 42. When this resonance is obtained the voltage in the pulsating plate circuit is increased and consequently more energy is impressed upon tranformer 44.

A non-regenerative receiving system is shown in Fig. 7 comprising two' steps of radio frequency amplification, a detector unit and one step of audio frequency amplification. In this dia am the two loop antennae 20 and. 29 are own connected in series,

with the turns of the loop 29 at the end thereof which is connected with the grid of the first tube spread in the manner and for the purpose previously described. With this arrangement radio energy received from any direction will be detected and amplified.

Fig. 8 shows a hook-up using another well known combination of a radio frequency amplification unit, a regenerative detector unit, and an audio frequency amplification unit. The novel part of the arrangement shown in'this figure is the way two loop antennae 20 and 20 at right angles to each other are used with a selective switch. One end of each loop is connected by a wire 45 through the variable condenser 41 with the coil 40 of a vario-coupler. The other end of the coil 40 is connected with a movable switch contact 47. The other end of loop 20 is connected to a switch contact 48 and the other end of loop 20 is connected to a switch contact 49. By this arrangement either of the loop antennae may be used.

Fig. 8 shows a further development of this thought. In this case two more loop antennae 20 and 20 are added between the antennae 20 and 20 with one end of each connected to switch contacts 48* and 49 respectively.

The diagram of Fig. 9 is another combination of radio and audio frequency amplifiers with a regenerative circuit. This diagram, however, shows what I now consider the preferable antenna arrangement. In this figure 50 is one loop antenna and 51 another loop antenna which is different from the first. These antennae are at right angles to each other and they are connected in multiple by having their likeends joined as at 52 and 53. The turns of each coil nearest the point 53 are spread as shown and as hereinbefore described. The loop 50 has a higher resistance than that of loop 51 and this result ma be obtained in any desired way, as by making loop 51 of smaller dimensions, of a'smaller number of turns or of larger gauge wire, or in all of these ways, as shown in the drawing, or by making it of wire of a different material. With this arrangement there are no zero pplints of reception. If either loop were pic 'ng up energy the whole system would oscillate. picking up energy and were opposln the system would oscillate into the con enser, If the loops were aiding and were of the same voltage there would be no difference of voltage across the condenser 41 and hence no oscillations inthe system. But as the loops are unbalanced by being of difierent resistance, there will be a difference of voltage across" the condenser.

Thus I have provided a self-contained receiving apparatus with no outside 'wires which is responsive to radiant energy from If both loops were I which is capable of amplifying the received radiant energy to any desired extent. It does not need to be manipulated by a skilled operator, but will operate in any room or place in which it is placed.

The invention upon which this application is based is broader than the specific embodiments thereof which have been shown and described and therefore I do notintend to limit myself to any particular construction or arrangement of parts, but intend only such limitations as are contained in the following claims,

What I claim is 2-- 1. In a radio apparatus, a loop antenna comprising a plurality of substantially parallel turns of wire unequally spaced.

2. In a radio apparatus, a loop antenna comprising a plurality of substantially parallel turns of wire with the turns at one end thereof spaced apart a greater distance than those at the other end.

In witness whereof, I have hereunto set my hand this 20th day of May, 1922.

DAVID GRIMES. 

